The present invention relates to a rotary switch mechanism for an operation panel that may be utilized in, for instance, an air-conditioning system for vehicles.
A rotary switch in the related art disclosed in Japanese Unexamined Patent Publication No. H 9-288934 comprises a switch board having a plurality of switch contact points, an elastic pressure application plate that includes a plurality of arm units and holds contact portions provided at the individual arm units on the switch contact points and a rotating body that is rotatably provided on the switch board and includes depressing portions provided at the lower surface of the switch board to come in contact with the arm units and thus push down the arm units.
It is necessary to secure ample space in conjunction with a rotary switch utilized in an air-conditioning system for vehicles in the related art since push switches and the indicator light source are sometimes provided on the printed board where the contact points of the rotary switch are located. For this reason, a problem arises with regard to utilization of the rotary switch in the quoted reference above in that the space in which push switches, the indicator light source and the like can be provided becomes limited since a large area of the printed board is occupied by the contact points. In addition, since the knob of the rotary switch is firmly secured to the contact points, it is difficult to accurately align the position of the knob hole formed at the operation panel with the position of the knob secured to the printed board, which gives rise to a problem with regard to the installation at the printed board.
Accordingly, an object of the present invention is to provide a rotary switch mechanism for an operation panel that allows ample space on a printed board, facilitates the design process for designing electronic parts and the like on the printed board and achieves good attachability for the switch knob.
In order to achieve the object described above, according to the present invention, on an operation panel with a plurality of mode settings, which allows one of the plurality of mode settings to be selected by selecting one of the positions corresponding to the plurality of mode settings, a cylindrical rotary knob that includes a portion projecting out at the front surface of the operation panel and is capable of stopping at each of the positions corresponding to the plurality of mode settings, drive pieces formed at specific phases at the circumferential edge at the end of the rotary knob located further inward at the operation panel that move along the circumference of the rotary knob as the rotary knob rotates and a detection switch that detects a passage of and the direction of the passage of the drive pieces are provided.
Thus, with the present invention, which simply requires the drive pieces to be provided over specific intervals at the circumferential edge at the end of the rotary knob located further inward at the operation panel and the detection switch for detecting a passage of and the direction of the passage of the drive pieces to be provided within or in the vicinity of the range of the movement of the drive pieces, e.g., on the printed board, ample space is assured on the printed board, thereby solving the problem discussed earlier.
In addition, the drive pieces formed at the rotary knob may project out along the radius of the rotary knob or they may project out along the axial direction from the external circumferential edge at the end of the rotary knob. It is desirable that the detection switch be constituted of a physical detection switch having a movable piece that is capable of moving along a direction corresponding to the direction of the passage of the drive pieces, and such a movable piece may be set either parallel to the drive pieces or perpendicular to the drive pieces.
The present invention is further characterized in that an intermediate transmission mechanism that converts the intervals between the individual drive pieces to a distance required for the movement of the movable piece is provided between the drive pieces and the movable piece. For instance, if the rotary knob has a smaller diameter and thus the intervals between the drive pieces, too, are smaller, the movement of the movable piece at the detection switch over such a small distance between the drive pieces cannot be detected. In such a case, by providing the intermediate transmission mechanism, it becomes possible to allow the movable piece of the detection switch to move over a large enough distance to allow a detection thereof.
In addition, the intermediate transmission mechanism should comprise a first arm that is caused to move by the drive pieces, a second arm that causes the movable piece to move and a supporting point portion provided between the first arm and the second arm, with the length of the first arm and the length of the second arm set in correspondence to the ratio of the interval between the drive pieces and the distance required for the movement of the movable piece. The first arm and the second arm may be set on a single straight line, may be set perpendicular to each other or may be set at a specific angle to each other. The drive pieces may each be constituted of a tooth of a drive gear formed at the end of the rotary knob and the intermediate transmission mechanism may be constituted of a working gear which interlocks with the drive gear and rotates as the drive pieces move and a working portion that is secured to the working gear and rotates as the working gear rotates to cause the movable piece to move, with the ratio of the number of teeth of the drive gear and the number of teeth of the drive gear and the number of the working portions set in correspondence to the ratio of the pitch at the drive gear and the distance required for the movement of the movable piece.
Furthermore, the rotary switch mechanism may include a plurality of detection switches positioned at phases different from the phases of the drive pieces and the individual detection switches may sequentially detect the passage of and the direction of the passage of the drive pieces while the drive pieces move over a distance equivalent to the interval between the individual drive pieces. By adopting this structure, in which a plurality of detection switches are positioned at phases different from the phases of the drive pieces, the individual detection switches can sequentially detect the passage of and the direction of the passage of the drive pieces while the drive pieces move over the distance equivalent to the interval between the drive pieces, i.e., while they pass over a single pitch of the drive pieces and a desired number of signals representing the rotational angle of the rotary knob corresponding to the number of drive pieces can be generated even when the intervals between the individual drive pieces is set large enough to allow the required movement of the movable piece.
While the detection switch is constituted of a physical detection switch that detects the passage of and the direction of the passage of the drive pieces by detecting the movement of the working piece in the example described above, the detection switch according to the present invention may be constituted of an optical detection switch having a light emitting element and a light receiving element, which detects the passage of and the direction of the passage of the drive pieces by detecting a change of light while the drive pieces pass between the light emitting element and the light receiving element instead.
Moreover, if a light emitting source for the indicator unit is provided at the center of the rotary knob, only the light receiving element may be provided to detect the passage of and the direction of the passage of the drive pieces. In addition, the detection switch may take on any structure as long as it is capable of detecting the passage of and the direction of the passage of the drive pieces through detection of a change occurring in an electromagnetic wave, an acoustic wave, an electrical field, a magnetic field or the like instead of a change of a visible light beam as described above.